Traditional electromechanical resistive track potentiometers or trimmers convert a manually set angular or linear position to a corresponding resistive divider ratio according to a mapping function, which, in principle, is continuous. The operating principle is based on an electrically conductive wiper, which is moved manually along or around a distributed track of resistive material, e.g. a carbon based material. Low resistance electrical contacts are provided at both ends of the track and also at the wiper, and such potentiometers provide a resistive division of a voltage applied at the ends of the track by translation of a linear or angular position of the movable part of the potentiometer.
Traditional electromechanical slide or rotational switches rely on a mechanical wiper with an electrically conductive tip or edge which opens or closes the electrical contact between two or more terminals of the switch. The opening and closing function of switches may then be used for selecting, enabling or disabling different parts of electric circuitry connected to the switch.
Traditional potentiometers, trimmers and switches are mechanical devices having moving parts in contact with each other, and wear is therefore unavoidable. The electrical performance of such elements is severely affected by the wear, and reliability problems often become pronounced in miniaturised elements.
U.S. Pat.No. 5,592,079 discloses such a known microelectric position sensor, however without any focusing of the magnetic field.
U.S. Pat.No. 4,258,346 discloses an arrangement including an assembly of magnetically actuated relays mounted adjacent a magnetic shield having an assembly of holes therein corresponding to the location of the relays. The shield prevents magnetic flux which is applied to one of the relays from being spilled over and inadvertently actuating a nearby relay.